1. Field of the Invention
This invention relates to a photoconductive member having sensitivity to electromagnetic waves such as light (herein used in a broad sense, including ultra-violet rays, visible light, infrared rays, X-rays and gamma-rays) and a support for said photoconductive member, particularly to an improved support and a photoconductive member having said support, which is suitable for use as a photosensitive member for electrophotography.
2. Description of the Prior Art
Amorphous silicon (hereinafter referred to as a-Si) in which dangling bonds are modified with monovalent elements is expected to be applied for an image forming member for electrophotography due to its excellent photoconductivity, friction resistance and heat resistance. Also, a-Si causes substantially no problem in environmental sanitation during preparation thereof, and, in addition, enlargement of area of a photosensitive member can also be made easily to an advantage in application.
However, a-Si alone may be sometimes slightly lower in dark resistance for use in a photosensitive member for electrophotography. Accordingly, this problem is generally solved by arrangement of an impeding layer for impeding charge injection from the support or by doping with an additive. There is a further problem that the surface becomes more affinitive for water since oxide film of SiO.sub.x will naturally be formed on a-Si surface under the environment under which an electrophotographic device is generally placed. If the device is used under such a state for an electrophotographic process in which corona discharging is frequently used, the surface charges will migrate on the surface of the photosensitive member under highly humid conditions, whereby a conventionally called unfocused image will be formed. For prevention of this, as the surface protective layer, SiN.sub.x, SiC.sub.x, etc. are arranged, and further a reflection prevention layer, a light absorbing layer, an adhesion layer, etc. are frequently provided, if necessary.
Thus, for providing a-Si in practical application as an electrophotographic photosensitive member, many kinds of gases are required to be employed to form the photoconductive member with a multi-layer constitution suitable for the purpose to a size useful as the electrophotographic photosensitive member. And, evenness of the photoconductive member in this case is very important. For example, if unevenness in photoconductive characteristics or defect such as pinhole exists, not only no beautiful image can be provided, but also such a photoconductive member is no longer useful in practical application.
The film morphology of a-Si is known to be greatly influenced by the surface shape of a support. In a photosensitive drum for electrophotography with a large area for which substantially the same photoconductive characteristics are required at almost all places, the surface condition of a support is very important, and presence of a projection or a recess on the surface of a support will impair the evenness of the film, whereby columnar structure or spherical projection may be formed to cause photoconductive unevenness.
Aluminum is a material which is preferable in many respects as a support for a photoconductive member, particularly a support as a photosensitive member for electrophotography. However, for the purpose of using an aluminum base material as the support, its surface is subjected to mirror finishing. In this process, there ensue various problems due to presence of hard portions called a hard spot. More specifically, this hard spot will make a cutting resistance against a cutting tool in the process of mirror finishing of the surface of the support, which may cause generation of failures on the surface of aluminum cylinder. For example, it may cause cracks of about 1 to 10 .mu.m, crater-like flaws, and further minute projection and recesses.
The present inventors have made extensive studies on this problem and consequently found that the hard spot, which is the cause of failures in the process of cutting of the surface of the support, is due to the impurity of various elements, including Fe, Ti and Si contained in aluminum. Among these impurities, particularly Fe will difficultly form a solid solution with aluminum, but forms an intermetallic compound of Fe-Al or Fe-Al-Si, which is dispersed as the hard spot in the aluminum matrix, and occurrence of this hard spot will be markedly increased at a specific Fe content or higher. It has also been found that Mg content within aluminum alloy is also concerned with the cutting characteristic of the aluminum alloy.
The present invention has been accomplished in view of the various points as described above, and it is based on a discovery that a photoconductive member excellent in evenness in photoconductive characteristics can be obtained by use of an aluminum alloy having a specific composition as the support for a-Si deposited film.